The infrared multiphoton dissociation (IRMPD) of CDCl₃ in the presence of O₂ and NO₂ as acceptor gases has been studied. We have worked with both pure CDCl₃ and mixtures with CHCl₃. The reaction mechanism following IRMPD of CDCl₃ is discussed in detail. CCl₂O, CCl₄ and DCl were found to be the main products. With added O₂, the observed CDCl₃ dissociation was larger than with nonoxygenated acceptor gases. The reaction mechanism probably involves a catalytic cycle initiated by the oxidation of CCl₃. With the aim of discriminating the different CDCl₃ dissociation mechanisms, the IRMPD of CDCl₃ in the presence of NO₂ was first studied. In order to make evident the CDCl₃ dissociation produced by the catalytic cycle, we then studied the IRMPD of CDCl₃ in mixtures with CHCl₃ with O₂ as the acceptor gas. In this case, the dissociation mechanism subsequent to IRMPD is evidenced in the competence between the two isotopic species.